In recent years, semiconductor devices become increasingly high-speed, high-capacity, and capable of processing larger bits data. At the same time, the semiconductor devices become more diversified. Burn-in test, which is an accelerated test depending on temperature conditions, is performed on the semiconductor device. The burn-in test is characterized by heating up a device under test (DUT) such as a semiconductor device through the application of electric currents to determine the reliability and the like of the DUT. For example, the test detects a local heat due to high resistance in a defective metal junction of a large scale integration (LSI) chip.
As an example of such a conventional technology, Japanese Patent Application Laid-Open No. 2000-206176 shows a burn-in test apparatus including a heater for testing semiconductor devices.
A conventional burn-in apparatus, which uses the heater, however, is unable to simultaneously test a plurality of DUTs that consume significantly different amount of power because it adjusts ambient temperature around the DUT by the heater.
It may be possible to adjust the temperature of each DUT by bringing the heater into contact with each DUT. Such temperature adjustment, however, requires a switching control with a power field effect transistor (FET) to follow changes in temperature. The switching control produces noises; the noise is transmitted to the DUT and thus makes it difficult to accurately perform the burn-in test.
In view of the foregoing, an object of the present invention is to provide a heater power control circuit and a burn-in apparatus using the circuit that reduce the noises transmitted from the heater when the burn-in test is performed by adjusting the temperature using the heater.